EES and the 90/180 rule: why the official calculator shows fewer days than my own count

Your interpretation is broadly on the right track, but there is an important point about the 90/180-day calculation.

The Schengen rule is not a fixed allowance calculated by simply adding the days from one previous trip to the days available on the current trip. For each day of stay, you look backwards at the previous 180 days and must not have been present in the Schengen area for more than 90 days during that moving period.

Based only on the dates you gave us — 12 April to 11 June 2026, followed by re-entry on 17 September — there was a long period outside Schengen between the two stays. As the days from your April–June stay progressively fall outside the rolling 180-day window, additional days can become available. This is why a result such as “28 days remaining” on a particular reference date should not automatically be interpreted as meaning that your entire new stay is limited to 28 days.

The European Commission's official short-stay calculator is designed to apply this rolling calculation. The Commission also explains that an uninterrupted absence of 90 days allows for a new stay of up to 90 days, subject of course to there being no other Schengen stays that affect the calculation.

A new passport does not create a new 90-day allowance. EES records are used to register and calculate entries/exits electronically, so you should continue to count all relevant Schengen stays, including those made using the previous passport.

Because a one-day difference or another Schengen trip can change the calculation, we would not advise relying on our calculation alone. Enter every entry and exit in the European Commission's official short-stay calculator and, if there is any doubt about your permitted stay, confirm it with the relevant border/immigration authority before relying on a particular departure date.

Official calculator and guidance: home-affairs.ec.europa.eu/policies/schengen/border-crossing/short-stay-calculator_en

Note: This is general information and not legal or immigration advice. The official calculator is a helping tool and the competent border/immigration authorities make the final determination in an individual case. If your permitted stay is important to a planned departure date or there is any uncertainty in your EES record, please confirm directly with the competent authority or an immigration lawyer.